Secretory phospholipase A2-mediated depletion of phosphatidylglycerol in early acute respiratory distress syndrome

IntroductionSecretory phospholipases A₂ (sPLA₂) hydrolyze phospholipids in cell membranes and extracellular structures such as pulmonary surfactant. This study tests the hypothesis that sPLA₂ are elevated in human lungs during acute respiratory distress syndrome (ARDS) and that sPLA₂ levels are associated with surfactant injury by hydrolysis of surfactant phospholipids.MethodsBronchoalveolar lavage (BAL) fluid was obtained from 18 patients with early ARDS (< 72 hours) and compared with samples from 10 healthy volunteers. Secreted phospholipase A₂ levels were measured (enzyme activity and enzyme immunoassay) in conjunction with ARDS subjects’ surfactant abnormalities including surfactant phospholipid composition, large and small aggregates distribution and surface tension function.ResultsBAL sPLA₂ enzyme activity was markedly elevated in ARDS samples relative to healthy subjects when measured by ex vivo hydrolysis of both phosphatidylglycerol (PG) and phosphatidylcholine (PC). Enzyme immunoassay identified increased PLA2G2A protein in the ARDS BAL fluid, which was strongly correlated with the sPLA₂ enzyme activity against PG. Of particular interest, the authors demonstrated an average depletion of 69% of the PG in the ARDS sample large aggregates relative to the normal controls. Furthermore, the sPLA₂ enzyme activity against PG and PC ex vivo correlated with the BAL recovery of in vivo PG and PC, respectively, and also correlated with the altered distribution of the large and small surfactant aggregates.ConclusionsThese results support the hypothesis that sPLA₂-mediated hydrolysis of surfactant phospholipid, especially PG by PLA2G2A, contributes to surfactant injury during early ARDS.     

Lung lymphocytes in bleomycin-induced pulmonary disease

Previous studies have not clearly defined the role of cell-mediated immunity in bleomycin-induced lung injury. In this report the functional activity of T lymphocytes obtained from minced lung preparations, bronchoalveolar lavage, and blood of rabbits treated with bleomycin was examined in cell proliferation and cell-mediated cytotoxicity assays. Four days after instillation of bleomycin (10 units/kg) into the right lung, histologic examination revealed mononuclear cell interstitial infiltrates and alveolar exudates. Right lung bronchoalveolar lavage (BAL) cell counts were similar in both groups, but the percentage of lymphocytes and neutrophils was elevated in bleomycin-treated groups (25% vs. 7% and 35% vs. 0% respectively;p<0.05). Spontaneous proliferation of cultured BAL and blood lymphocytes was similar in bleomycin-treated rabbits and controls. After 24 h of incubation with interleukin-2 (IL-2), BAL lymphocytes from bleomycin-treated rabbits had nearly a 4-fold greater proliferative response than lymphocytes from untreated rabbits. Concanavalin-A-dependent cell-mediated cytotoxicity (CDCMC) assays were performed to evaluate cytolytic lymphocyte activity. Spontaneous CDCMC activity was not detected in BAL fluid or in blood lymphocytes from either treated or control animals. After 24 h of incubation with IL-2, significant CDCMC activity was detected in lung lymphocytes from bleomycin-treated animals, but not in lung lymphocytes from control animals. These results indicate that stimulated lymphocytes are present in the lungs of rabbits 4 days after exposure to bleomycin. Presented in part at the American Thoracic Society Annual Meeting, New Orleans, LA, May 1987.     

Procoagulant activity in bronchoalveolar lavage in the adult respiratory distress syndrome. Contribution of tissue factor associated with factor VII

Alveolar fibrin deposition commonly occurs in the lungs of patients with the adult respiratory distress syndrome (ARDS). Bronchoalveolar lavage (BAL) from patients with ARDS, control patients with interstitial lung disease (ILD), congestive heart failure, or exposure to hyperoxia, and normal healthy subjects was studied to determine whether local alterations in procoagulant activity favor alveolar fibrin deposition in the lungs in ARDS. Procoagulant activity capable of shortening the recalcification time of plasma deficient in either factor VII or factor VIII was observed in unconcentrated BAL of all patients, but was significantly greater in BAL from patients with ARDS when compared with that of control subjects (p less than 0.001). Unconcentrated BAL from patients with ARDS shortened the recalcification time of plasma deficient in factor X, but no functional thrombin was detectable. BAL procoagulant from patients with ARDS was inhibited by concanavalin A, an inhibitor of tissue factor. The hydrolysis of purified human factor X by BAL from the ARDS and other patient groups was determined by measuring the amidolytic activity of generated factor Xa on its N-benzoyl-L-isoleucyl-L-glutamyl-glycyl-L-arginine-p-nitroanilide substrate. The procoagulant activity of BAL was associated with the development of amidolytic activity, indicating activation of factor X. BAL from patients with ARDS contained more factor X activating activity than did BAL from control groups (p less than 0.001). This activity was calcium dependent and was maximal at 1 mM ionized calcium. The BAL factor X activating activity was most active at neutral pH and was sedimented by ultracentrifugation at 100,000 x g.(ABSTRACT TRUNCATED AT 250 WORDS)     

Neutrophil elastase-releasing factors in bronchoalveolar lavage from patients with adult respiratory distress syndrome

Bronchoalveolar lavage fluid (BAL) was obtained from patients with adult respiratory distress syndrome (ARDS). Controls included BAL from normal subjects and from patients with sarcoidosis or pulmonary fibrosis. Neutrophil elastase measured immunologically was found in all BAL samples, but it was strikingly greater in BAL from patients with ARDS than in the BAL from normal subjects or patients with sarcoidosis. There was no significant difference in the neutrophil elastase antigen concentrations in BAL samples from patients with ARDS and those with pulmonary fibrosis. No elastolytic activity was found in either group. The alpha-1-antitrypsin and the bronchial mucus inhibitor were greater in BAL from patients with ARDS. There was a highly significant correlation between the alveolar-arterial oxygen tension difference and the neutrophil elastase concentration in BAL from the patients with ARDS. Kallikrein, prekallikrein, factor XIa-like activity, and high molecular weight kininogen antigen were found in BAL of patients with ARDS, suggesting that the kallikrein-kinin cascade may be activated in the lungs of patients with ARDS. Kallikrein-like activity in the BAL from the patients with ARDS was significantly correlated with the number of neutrophils in the BAL, the neutrophil elastase concentration, and the ability of the BAL to release elastase from cytochalasin-B-treated neutrophils. There was no correlation between these variables and C5a concentration. These studies demonstrated an association between BAL neutrophil elastase and the clinical state of patients with ARDS.     

Kupffer-cell activity is essential for thyroid hormone rat liver preconditioning

We studied the role of Kupffer cell functioning in T₃ liver preconditioning against ischemia–reperfusion (IR) injury using the macrophage inactivator gadolinium chloride (GdCl₃) previous to T₃ treatment. Male Sprague–Dawley rats given a single i.p. dose of 0.1 mg T₃/kg were subjected to 1 h ischemia followed by 20 h reperfusion, in groups of animals pretreated with 10 mg GdCl₃/kg i.v. 72 h before T₃ or with the respective vehicles. IR resulted in significant enhancement of serum aspartate aminotransferase (3.3-fold increase) and tumor necrosis factor-α (93% increase) levels, development of liver damage, and diminished nuclear factor-κB DNA binding over control values. These changes, which were suppressed by the T₃ administration prior to IR, persisted in animals given GdCl₃ before T₃ treatment, under conditions of complete elimination of ED2(+) Kupffer cells achieved in a time window of 72 h. It is concluded that Kupffer cell functioning is essential for T₃ liver preconditioning, assessed in a warm IR injury model by hepatic macrophage inactivation.     

N-acetyl-beta-D-glucosaminidase activity within BAL from macaques exposed to generic coal dusts

N-acetyl-beta()-D-glucosaminidase is a lysosomal enzyme secreted by alveolar macrophages in response to phagocytosis of particulate material. Alveolar macrophages participate in the degradation and fibrosis of pulmonary tissue that results in pneumoconiosis. Known quantities of four characterized respirable dusts were bronchoscopically placed into the right caudal lung lobe of macaque monkeys. Bronchoalveolar lavage (BAL) samples were collected from dust-exposed right lung and unexposed left lung of the same individuals at 2-week intervals for 12 weeks after dust instillation. The samples were tested for N-acetyl--D-glucosaminidase activity to determine if the enzyme levels could serve as an indicator of pulmonary injury induced by generic coal dusts when compared to known fibrogenic and nuisance dusts. Installation of generic quartz, anthracite, or TiO₂ dusts produced significant elevations of enzyme activity and increased numbers of macrophages in the dust-exposed lobes. Elevations in enzymatic activity and macrophage numbers were greatest in response to generic quartz dust. These results suggest that quantitative levels of N-acetyl--D-glucosaminidase activity may be a useful indicator of acute and chronic lung injury following exposure to fibrogenic and nonfibrogenic dusts.Offprint requests to: J. W. Griffith     

Nitric oxide and nitrotyrosine in the lungs of patients with acute respiratory distress syndrome

Nitric oxide (NO) end-products (nitrate and nitrite) are present in bronchoalveolar lavage (BAL) fluid of patients with inflammatory lung diseases. Reactive oxygen-nitrogen intermediates damage macromolecules by oxidation or nitration of critical residues in proteins. The goal of this study was to measure NO end-products (nitrate+ nitrite), in BAL fluid before and after the onset of acute respiratory distress syndrome (ARDS) and to determine if these products are associated with expression of inducible nitric oxide synthase enzyme (iNOS) in BAL cells and nitration of BAL proteins. We performed bronchoalveolar lavage (BAL) in patients at risk for ARDS (n = 19), or with ARDS (n = 41) on Days 1, 3, 7, 14, and 21 after onset, and measured total nitrite (after reducing nitrate to nitrite) and protein-associated nitrotyrosine concentration in each BAL fluid sample. Cytospin preparations of BAL cells were analyzed by immunocytochemistry for iNOS and nitrotyrosine. Nitrate+nitrite were detected in BAL fluid from patients at risk for ARDS, and for as long as 21 d after the onset of ARDS. Nitrotyrosine was detectable in all BAL fluid samples for as long as 14 d after the onset of ARDS (range, 38.8 to 278.5 pmol/mg of protein), but not in BAL of normal volunteers. Alveolar macrophages of patients with ARDS were positive for iNOS and nitrotyrosine, and remained positive for as long as 14 d after onset of ARDS. The BAL nitrate+nitrite did not predict the onset of ARDS, but the concentration was significantly higher on Days 3 and 7 of ARDS in patients who died. Thus, NO end products accumulate in the lungs before and after onset of ARDS; iNOS is expressed at high levels in AM during ARDS; and nitration of intracellular and extracellular proteins occurs in the lungs in ARDS. The data support the concept that NO-dependent pathways are important in the lungs of patients before and after the onset of ARDS.     

Fibroproliferation occurs early in the acute respiratory distress syndrome and impacts on outcome

The fibroproliferative phase of acute respiratory distress syndrome (ARDS) has traditionally been regarded as a late event but recent studies that suggest increased lung collagen turnover within 24 h of diagnosis challenge this view. We hypothesized that fibroproliferation is initiated early in ARDS, characterized by the presence of fibroblast growth factor activity in the lung and would relate to clinical outcome. Patients fulfilling American/European Consensus Committee criteria for ARDS and control patients ventilated for non-ARDS respiratory failure underwent bronchoalveolar lavage (BAL) and serum sampling within 24 h of diagnosis and again at 7 d. The ability of BAL fluid (BALF) to stimulate human lung fibroblast proliferation in vitro was examined in relation to concentrations of N-terminal peptide for type III procollagen (N-PCP-III) in BALF/serum and clinical indices. At 24 h, ARDS lavage fluid demonstrated potent mitogenic activity with a median value equivalent to 70% (range 31-164) of the response to serum, and was significantly higher than control lavage (32% of serum response, range 11-42; p < 0.05). At 24 h, serum N-PCP-III concentrations were elevated in the ARDS group compared with control patients (2.8 U/ml; range 0.6-14.8 versus 1.1 U/ml; range 0.4-3.7, p < 0.0001) as were BALF N-PCP-III concentrations (2.9 U/ml; range 0. 6-11.4 versus 0.46 U/ ml; range 0.00-1.63, p < 0.01). In addition, BALF N-PCP-III concentrations at 24 h were significantly elevated in nonsurvivors of ARDS compared with survivors (p < 0.05). At 7 d, the mitogenic activity remained elevated in the ARDS group compared with control (p < 0.05) and was also significantly higher in ARDS nonsurvivors compared with survivors (67%; range 45-120 versus 31%; range 16-64, p < 0.05). These data are consistent with the hypothesis that fibroproliferation is an early response to lung injury and an important therapeutic target.     

Bronchoalveolar neutrophilia inversely correlates with DLCO at diagnosis in asbestosis but not lung function decline at 1 year

The role of bronchoalveolar lavage (BAL) in the assessment of interstitial lung disease (ILD) remains controversial. Previous studies have demonstrated that BAL cell differential is useful in predicting disease progression in many forms of ILD. We wished to investigate whether BAL had a similar use in predicting disease progression in asbestosis. 21 patients who had significant asbestos exposure, findings of UIP radiologically and BAL performed as part of their investigation were reviewed. There was a significant inverse correlation between percentage BAL neutrophils and percentage predicted DL_CO at diagnosis (n=21; P=0.02; r²=^–0.25; CI, ^–0.77^-0.08), but not with DL_CO decline over 1 year. Unlike previous reports in IPF, BAL cell differential is not predictive of decline in classic asbestosis with a UIP pattern and its routine use in this cohort of patients provides little if any additional benefit.KEY WORDS : Bronchoalveolar lavage (BAL), asbestosis, neutrophilia, lung function     

Lung lymphocytes in bleomycin-induced pulmonary disease

Previous studies have not clearly defined the role of cell-mediated immunity in bleomycin-induced lung injury. In this report the functional activity of T lymphocytes obtained from minced lung preparations, bronchoalveolar lavage, and blood of rabbits treated with bleomycin was examined in cell proliferation and cell-mediated cytotoxicity assays. Four days after instillation of bleomycin (10 units/kg) into the right lung, histologic examination revealed mononuclear cell interstitial infiltrates and alveolar exudates. Right lung bronchoalveolar lavage (BAL) cell counts were similar in both groups, but the percentage of lymphocytes and neutrophils was elevated in bleomycin-treated groups (25% vs. 7% and 35% vs. 0% respectively; p less than 0.05). Spontaneous proliferation of cultured BAL and blood lymphocytes was similar in bleomycin-treated rabbits and controls. After 24 h of incubation with interleukin-2 (IL-2), BAL lymphocytes from bleomycin-treated rabbits had nearly a 4-fold greater proliferative response than lymphocytes from untreated rabbits. Concanavalin-A-dependent cell-mediated cytotoxicity (CDCMC) assays were performed to evaluate cytolytic lymphocyte activity. Spontaneous CDCMC activity was not detected in BAL fluid or in blood lymphocytes from either treated or control animals. After 24 h of incubation with IL-2, significant CDCMC activity was detected in lung lymphocytes from bleomycin-treated animals, but not in lung lymphocytes from control animals. These results indicate that stimulated lymphocytes are present in the lungs of rabbits 4 days after exposure to bleomycin.     

β-Adrenoceptor and adenylate cyclase regulation in cardiac myocyte growth

Summary We studied the effect of growth on -adrenergic receptor properties of neonatal rat heart myocytes cultured in serum-free medium with transferrin and insulin. Growth was induced by addition of 1 M (–)-norepinephrine for two days, 200 nM of the tumor-promoting phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) for two days, or 30 nM T₃ for six days. The K_d values for -receptor binding (¹²⁵I-ICYP) were unaffected by growth. The maximum number of -receptor binding sites calculated as sites/cell was increased 1.47-fold by T₃ (p<.005), but was decreased to 54% of control values by (–)-norepinephrine (p<.005); TPA had no effect on either Kd or B_max values. (–)-Isoproterenol-stimulated adenylate cyclase activity was augmented only in membranes from T₃-treated cells and was reduced by 69% in membranes from (–)-norepinephrine treated cells. TPA had no effect on(–)-isoproterenol-stimulated adenylate cyclase activity. We conclude that the mechanisms controlling -adrenergic receptor number may be distinct from those controlling growth, since receptor number does not correlate with cell enlargement. Furthermore, in (–)-norepinephrine-stimulated growth, which we have shown previously is an ₁-adrenoceptor mediated response, -adrenergic signal transduction is modulated in a directionally opposite fashion.Supported by grants from the Veterans Administration Research Service, American Heart Association California Affiliate, and National Heart, Lung, and Blood Institute Grant HL31113. Dr. Simpson is a Clinical Investigator of the Veterans Administration Research Service.     

Montelukast versus inhaled corticosteroids in the management of pediatric mild persistent asthma

Background

Lung tissue of patients with acute respiratory distress syndrome (ARDS) is heterogeneously damaged and prone to develop atelectasis. During inflation, atelectatic regions may exhibit alveolar recruitment accompanied by prolonged filling with air in contrast to regions with already open alveoli with a fast increase in regional aeration. During deflation, derecruitment of injured regions is possible with ongoing loss in regional aeration. The aim of our study was to assess the dynamics of regional lung aeration in mechanically ventilated patients with ARDS and its dependency on positive end-expiratory pressure (PEEP) using electrical impedance tomography (EIT).

Methods

Twelve lung healthy and twenty ARDS patients were examined by EIT during sustained step increases in airway pressure from 0, 8 and 15 cm H₂O to 35 cm H₂O and during subsequent step decrease to the corresponding PEEP. Regional EIT waveforms in the ventral and dorsal lung regions were fitted to bi-exponential equations. Regional fast and slow respiratory time constants and the sizes of the fast and slow compartments were subsequently calculated.

Results

ARDS patients exhibited significantly lower fast and slow time constants than the lung healthy patients in ventral and dorsal regions. The time constants were significantly affected by PEEP and differed between the regions. The size of the fast compartment was significantly lower in ARDS patients than in patients with healthy lung under all studied conditions.

Conclusion

These results show that regional lung mechanics can be assessed by EIT. They reflect the lower respiratory system compliance of injured lungs and imply more pronounced regional recruitment and derecruitment in ARDS patients.     

Regional differences in bronchoalveolar lavage and thoracic high‐resolution computed tomography results in dyspneic patients with systemic sclerosis

Objective

Interstitial lung disease (ILD) is the leading cause of death in systemic sclerosis (SSc). Although early identification and treatment of alveolitis may prevent deterioration of lung function, the best approach for diagnosing active alveolitis remains controversial. This study was undertaken to investigate the utility of high‐resolution computed tomography (HRCT) of the chest, in comparison with bronchoalveolar lavage (BAL), in the diagnosis of alveolitis in these patients.

Methods

Eighteen patients with SSc and dyspnea were evaluated for ILD by pulmonary function testing and bronchoalveolar lavage (BAL), and 15 of these patients underwent chest HRCT. BAL was performed in either the middle lobe or the lingula, and also in a lower lung segment. Differential cell counts were determined by clinical cytopathology, with retrospective recounting in a blinded manner by a single technician. Active alveolitis was defined as the presence of ≥3.0% polymorphonuclear cells and/or ≥2% eosinophils in BAL fluid. BAL fluids were cultured for bacteria, mycobacteria, and fungi. HRCT scans were evaluated in a blinded manner for ground‐glass opacification and fibrosis in the lavaged lobes.

Results

Nine of the 18 patients had active alveolitis recorded in both lavaged segments, while in 4 patients it was recorded in only 1 segment (lower lobe in 3). Following repeat differential cell counting, 3 patients were reclassified as having active alveolitis and 1 as having no alveolitis. Culture of BAL fluid identified clinically unsuspected infection in 3 patients. For the right middle lung lobe or lingula there was excellent agreement between ground‐glass opacification and the finding of alveolitis on BAL from segments in the same lung regions, but this was not observed for the lower lobes. The correlation between fibrosis on HRCT and the presence of alveolitis on BAL was significant for the lower lobes but not the middle lung fields.

Conclusion

BAL of the middle lobe or lingula may underestimate the presence of active alveolitis. Similarly, while ground‐glass opacification on HRCT accurately predicted alveolitis in the middle lung fields, HRCT did not detect all sites of inflammation and did not identify infectious etiologies. These data suggest that, in addition to HRCT, BAL with lavage, differential cell counting, and culture from at least 2 segments of lung be performed for diagnosing SSc alveolitis.

     

Early biochemical reactions in the lung of sheep exposed to asbestos: Evidence for cyclic AMP accumulation in bronchoalveolar lavage fluids

A conscious sheep model which allows sequential analysis of the bronchoalveolar milieu was used to investigate the early biochemical events following asbestos exposure. Segmental bronchoalveolar lavages (BAL) were performed in a group of 15 sheep exposed to repeated doses of UICC chrysotile B asbestos (0–128 mg) over a six month period. BAL cell population was analysed and various humoral components including total proteins, albumin, alpha₁-globulins (α ₁), alpha₂-globulins (α ₂), beta + gamma globulins (β+γ) and adenosine 3′,5′-cyclic monophosphate (cAMP) were determined in cell free supernates. All animals were also studied by pulmonary function tests (PF) and transbronchial lung biopsies (LB). Exposure to asbestos (up to 128 mg/month) did not cause any significant alteration of pulmonary functions and lung histology. However, analyses of the BAL effluent revealed that BAL fluids of sheep exposed to asbestos contained higher levels ofα ₁-globulins and cyclic AMP as compared to controls. Furthermore this phenomenon was observed without overall change of BAL cell population except for a significant eosinophilia in the asbestos-exposed animals. These data demonstrate that the early biochemical response of sheep exposed to asbestos is characterized by a significant eosinophilia and increases ofα ₁-globulins and cyclic AMP in the bronchoalveolar milieu. These biochemical events may be involved in the chronic inflammatory reaction to asbestos and possibly in the fibrogenic response.

     

Platelet-specific alpha-granule proteins and thrombospondin in bronchoalveolar lavage in the adult respiratory distress syndrome

Levels of platelet-specific alpha-granule proteins, PF, BTG, and TSP were measured in BAL fluids of patients with the ARDS, ILD, and normal healthy subjects, comprising two separate cohorts. In both groups BAL showed elevated levels of BTG and thrombospondin in ARDS patients. Low levels of PF4 were found in BAL and did not differ between ARDS and control patients. The BTG:PF4 ratio was 2:1 or greater in BAL of ARDS patients and of control subjects with other lung diseases, suggesting in vivo release. In ARDS patients, the ratio of TSP to BTG exceeded that usually found in plasma. In ARDS patients in group 2, BAL levels of TSP, BTG, and total protein correlated strongly with the composite injury scores that were used to quantitate their degree of lung injury. Elevated levels of platelet-derived proteins, which modulate chemotaxis of inflammatory cells and promote connective tissue reorganization, occur in the alveolar compartment of ARDS and ILD patients but are usually undetectable in BAL of healthy control subjects. Levels in these patients in BAL fluid are nonspecific indices of the severity of lung injury in patients with ARDS.     

Biofire pneumonia panel in lung donors: faster detection but limited pathogens

Background

Culture of bronchoalveolar lavage (BAL) specimens takes time to report. We tested whether a molecular diagnostic test could accelerate donor lung assessment and treatment.

Methods

We compared BioFire Film Array Pneumonia Panel (BFPP) with standard of care (SOC) tests on lung allograft samples at three time points: (1) donor BAL at organ recovery, (2) donor bronchial tissue and airway swab at implantation, and (3) first recipient BAL following lung implantation. Primary outcomes were the difference in time to result (Wilcoxon signed-ranked tests) and the agreement in results between BFPP and SOC assays (Gwet's agreement coefficient).

Results

We enrolled 50 subjects. In donor lung BAL specimens, BFPP detected 52 infections (14 out of 26 pathogens in the panel). Viral and bacterial BFPP results were reported 2.4 h (interquartile range, IQR 2.0–6.4) following BAL versus 4.6 h (IQR 1.9–6.0, p = 0.625) for OPO BAL viral SOC results and 66 h (IQR 47–87, p < .0001) for OPO BAL bacterial SOC results. Although there was high overall agreement of results between BAL–BFPP versus OPO BAL–SOC tests (Gwet's AC p < .001 for all), the level of agreement differed among 26 pathogens designed in BFPP and differed by types of specimens. BFPP could not detect many infections identified by SOC assays.

Conclusions

BFPP decreased time to detection of lung pathogens among donated lungs, but it cannot replace SOC tests due to the limited number of pathogens in the panel.

     

Angiotensin converting enzyme in bronchoalveolar lavage in ARDS

Angiotensin converting enzyme (ACE) is present in the endothelial cells of the normal lung where it converts angiotensin I to angiotensin II and inactivates bradykinin. It has been suggested that during endothelial injury ACE is sloughed into the blood, and that if the alveolar capillary membrane is injured, also into the alveolar lining fluid. Seven patients with adult respiratory distress syndrome (ARDS), were compared to 11 normal control subjects, nine patients with sarcoidosis, and six with idiopathic pulmonary fibrosis. Total, differential cell counts and ACE determinations were performed on bronchoalveolar lavage fluid in the ARDS group. ACE was detectable in the BAL of all but one ARDS patient. It was concluded that BAL ACE is elevated in some ARDS patients, especially those with infectious causes of lung injury. Increased ACE may reflect endothelial damage or local increase in ACE production in response to sepsis.     

Comparison between lung parenchyma and bronchoalveolar lavage collagenolytic activity

We have evaluated, in an experimental model of silicosis in guinea pigs, if the presence of collagenolytic activity in bronchoalveolar lavage (BAL) fluid reflects the collagen catabolism in lung parenchyma. We measured simultaneously BAL collagenase activity, using as substrate [³H]type I collagen, and lung collagenolytic activity by the tissue pellet assay. Animals (n = 30) were instilled intratracheally with 50 mg of quartz DQ-12 and sacrificed 15, 30, and 60 days after silica administration. Guinea pigs instilled with saline solution were used as controls. Our results showed that lung parenchymal collagenolytic activity was present in all experimental and normal guinea pigs. There were no statistical differences between silicotic and normal animals at 15 and 30 days. At 60 days, however, a significant decrease in tissue collagenolytic activity was observed in silicotic animals (161 ± 100 vs. 400 ± 152 units of collagenase activity; p < 0.001). In contrast, BAL collagenolytic activity was revealed only in 7 of 10 silicotic animals at 15 days and 30 days, and in 4 of 10 at 60 days. Normal guinea pigs did not exhibit BAL collagenase activity. BAL and tissue collagenase activity from each experimental animal were analyzed by straight line regression and no significant relationship was observed (r = 0.082; p = 0.87). This suggests that BAL collagenolytic activity does not reflect lung tissue collagen turnover. Offprint requests to: M. Selman     

Serial changes in surfactant-associated proteins in lung and serum before and after onset of ARDS

The goal of this study was to determine the changes that occur in surfactant-associated proteins in bronchoalveolar lavage fluid (BAL) and serum of patients at risk for ARDS and during the course of ARDS. We found that the concentrations of SP-A and SP-B were low in the BAL of patients at risk for ARDS before the onset of clinically defined lung injury, whereas the concentration of SP-D was normal. In patients with established ARDS, BAL SP-A and SP-B concentrations were low during the entire 14-d observation period, but the median SP-D concentrations remained in the normal range. Immunoreactive SP-A and SP-D were not increased in the serum of patients at risk for ARDS, but both increased after the onset of ARDS to a maximum on Day 3 and remained elevated for as long as 14 d. The BAL SP-A concentrations were significantly lower in at-risk patients who developed ARDS, and no patient with a BAL SP-A concentration greater than 1.2 microg/ml developed ARDS. On Days 1 and 3 of ARDS, the BAL SP-D concentration was significantly lower in patients who died, and the BAL SP-D concentration was significantly related to the PI(O(2))/FI(O(2)) ratio. Thus, surfactant protein abnormalities occur before and after the onset of ARDS, and the responses of SP-A, SP-B, and SP-D differ in important ways. The BAL SP-A and SP-D measurements can be used to classify patients as high or low risk for progression to ARDS and/or death after the onset of ARDS. Strategies to increase these surfactant proteins in the lungs of patients with ARDS could be useful to modify the onset or the course of ARDS.     

Functional loss of chemotactic factor inactivator in the adult respiratory distress syndrome

The adult respiratory distress syndrome (ARDS) is often characterized by a neutrophilic alveolitis, which may be mediated in part by the neutrophil chemoattractant, C5a. Chemotactic factor inactivator (CFI) can decrease C5a-directed neutrophil chemotaxis. Thus, a loss of CFI activity in the ARDS lung could lead to an increased ability of C5a to attract neutrophils. Lung CFI levels were measured antigenically and functionally in bronchoalveolar lavage (BAL) fluid obtained from 29 patients with ARDS and in 14 normal control subjects. Antigenic levels of CFI were found to be markedly elevated in ARDS BAL fluid (1,855 +/- 437 ng/ml) compared with that in normal BAL (29 +/- 10 ng/ml, p less than 0.005), but, in contrast, CFI functional activity was markedly decreased in ARDS BAL fluid compared with that in normal BAL fluid (31 +/- 7% inhibition versus 76 +/- 5% inhibition, p less than 0.01). Furthermore, although purified CFI readily inhibited the ability of C5a to attract neutrophils (92% inhibition), this activity was decreased when BAL fluid from patients with ARDS was incubated with CFI (47 +/- 10%, p less than 0.01). These findings suggest that patients with ARDS are functionally deficient in CFI, leading to an increased ability of C5a to attract neutrophils.